PV Cell and Module Calibra0ons at NREL

PV  Cell  and  Module   Calibra0ons  at  NREL    

PV  Asia  Pacific  Expo     October  23-­‐25,  2012   Keith  Emery   Symposium:  Accurate  Measurements   of  PV  Cells  and  Modules   NREL  is  a  na*onal  laboratory  of  the  U.S.  Department  of  Energy,  Office  of  Energy  Efficiency  and  Renewable  Energy,  operated  by  the  Alliance  for  Sustainable  Energy,  LLC.  

Outline   o  Mission   o  Primary  Refenerce  Cell  Calibra*ons   o  Secondary  cell  calibra*ons  

– QE  Measurement   – Linearity  Measurement   – Temperature  Coefficient  Measurement   – I-­‐V    single  junc*on    Mul*junc*on   o  Concentrator  cell   o  Concentrator  Moudle   o  Flat  Plate  module   o  Summary   2  

Mission   •  Daily  PV  Performance  Measurement  Technology  transfer  to   community  via  emails,  phone  calls  and  1/2  day  to  several  days   consul*ng  at  NREL   •  Assist  cer*fied  test  labs  with  calibra*on  traceability,   uncertainty  analysis,  procedures  and  error  sources.   •  Ac*ve  in  ASTM  and  IEC  photovoltaic  standards  development  

Standard  Repor0ng  (Test)  Condi0ons   PV  Temperature:  25  °C     Total  Irradiance:  1000  Wm-­‐2   Reference  spectrum:  Tabular   3  

Mission   •  Performance  measurements  for  any  conceivable  PV   cell  or  modules  technology  of  any  size  or  shape   •  Primary  terrestrial  reference  cell  calibra*ons   •  Secondary  reference  cell  and  module  calibra*ons  for   the  PV  community   •  Independent  efficiency  measurement  for  PV   community  and  contract  deliverables   •  ISO  17025  accredita*on  applies  to  a  narrow  scope  of   samples.    The  same  hardware,  soZware,  and  quality   system  used  for  all  measurements.  

4  

SRRL  

 Broadband  Radiometer  Calibra*ons  for  U.S.  

 Spectral  Radiometer  calibra*on    Volt,  Ohm,  Amp,  Temperature  

OTF-­‐Module  calibra*ons  

SERF-­‐Cell  calibra*ons  

5  

Calibra0on  –  Peak  WaT  Ra0ng   Pmax Efficiency ! " ! 100 Etot A

To  be  uniquely  specified:   Pmax = maximum  electrical  power  produced  when  illuminated  at  standard  reference  (test)   condi*ons  defined  by  a  temperature,  spectral  and  total  irradiance     A = area  of  the  device   Etot = total  irradiance  at  standard  reference  (test)  condi*ons,  1000  Wm-­‐2   !2

1=

I

R, R

I R,S M

Where:  

!2

" E ( ! ) S ( ! ) d! " E ( ! ) S ( ! ) d! Ref

M=

Ref

!1 !2

S

T

!1 !2

" E ( ! ) S ( ! ) d! " E ( ! ) S ( ! ) d! Ref

!1

T

S

Ref

!1

IR,R,  (IR,S)  =  reference  cell  short-­‐circuit  current  under  reference  (source)  spectrum   ERef(λ)  =  reference  (photon  flux)  spectral  irradiance   ES(λ)  =  simulator  (photon  flux)  spectral  irradiance   SRef(λ)  =  reference  (quantum  efficiency)  spectral  responsivity   ST(λ)  =  test  cell  (quantum  efficiency)   6  

NREL  Primary  PV  Calibra0on  

7  

External  Intercomparisons  are  Cri0cal   •  Compare  your  results:   •  As  many  labs  as   possible   •  As  oZen  as  possible   •  As  many  different   samples  as  possible  

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Isc  Linearity    

Linearity  test  bed  to  demonstrate  that  Isc  is  linear  with  irradiance  as   required  in  reference  cell  calibra*on  and  IV  measurement  standards.     9  

Isc  linearity  with  irradiance   0.3

Variation from linearity (%)

0.2

0.1

0.0

-0.1

PTB  method  based  upon   absolute  QE  vs.  bias  light  

-0.2

PTB 6-04 PTB PEP’93

-0.3

NREL 2 lamp method -0.4 0.0

0.2

0.4

0.6 0.8 Number of Suns

1.0

PTB  method  is  the  most  correct  procedure  because  it   relies  on  the  change  Jsc  from  the  absolute  QE  vs.  bias  light.    

1.2

1.4

K.  Emery,  S.  Winter,  et  al,   Linearity   Tes*ng  of  Photovoltaic  Cells,  Proc.  4th   World  PVSEC,  pp.  2177-­‐2180,  2006   10  

Cell  I-­‐V  Equipment

   

I-V Applications

Light source

size/temperature

Voltage

Current

1-sun

Spectrolab X25

30 cm x 30 cm

±0.5 mV

±10 pA Continuous

filtered 3 kW Xe

5-50 °C

±50 V

±16 A



0.1 - 20 suns

 

Continuous

1 kW Xe

~ 1 cm diameter

±0.1 mV

±1 µA

Concentrator

1 to 200 suns

5-80 °C

±10V

±10 A







 

Pulsed

Spectrolab LAPSS

2 Xe flash lamps

1 mV

1 mA

Concentrator

Spectrolab HIPSS

2 lamps & mirrors

100 V

50 A



2 reference channels



Multi-source spectrally adjustable 0.1 to 1-sun operational. Demonstrated for 6 junctions that can set photocurrent within 1% for each junction.



Spectrally adjustable concentrator Spectrolab THIPSS operational in 6 months.

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Spectrolab X25 Solar Simulator    

luck

3  s  shuker   25  ms  shuker   Spectrolab  X-­‐25  Solar  Simulator   Flexible   probe   sta*on   Temperature  controlled   intensity  monitor  and   vacuum  plate  

I-­‐V  rack   ±  0.1  mV  to  50  V   ±  10  pA  to  16  A   Primary   referenc e  cells  

Computer-­‐  Labview  based   all  data  text  files,  directory  and   data  file  saved  to  2  hard  drives,   common  format  all  test  beds,  file   naming   test  bed  YYMMDD-­‐ HHMMSS   12  

10-­‐Channel  One-­‐Sun   Solar  Simulator  

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6-­‐junc0on  result  

Tom  Moriarty,  Joe  Jablonski,  Keith   Emery  ,”Algorithm  for  Building  a   Spectrum  for  NREL  One-­‐Sun  Mul*-­‐ Source  Simulator,”  38th  IEEE   Photovoltaic  Spec.  Conf.,  Aus*n,  TX,   June  3-­‐8,  2012.    

All  photo-­‐current  ra*os  less  then  0.5%!   14  

Concentrator  Cells  

Con*nuous  and  flash  concentrated  light   opera*ng  from  1  to  100  suns  con*nuous   and  1  to  2000  suns  for  the  flash  system   mA  to  50A   mV  to  100V   15  

Concentrator  cells  

GaInP  /  GaAs  filtered  Ge  

1.2  

GaInP  /  filtered  GaAs  

1.0   0.8  

!Q !Q

top bot

AMO/3200  V  

AMO/2200  V  

AMO/1200  V  

LO  AOD  direct/3200  V  

LO  AOD  direct/2200  V  

LO  AOD  direct/1200  V  

ASTM  E891  dir/3200  V  

0.4  

ASTM  E891  dir/1200  V  

0.6   ASTM  E891  dir/1200  V  

Ra*o  of  Jsc s  

1.4  

Eref d" ! Qbot EV Eref d" ! Qtop EV

lamp

d"

d"

J.  Kiehl,  K.  Emery  and  A.  Andreas,  ”Tes*ng   Concentrator  Cells:  Spectral  Considera*ons   of  a  Flash  Lamp  System,”  Proc.  19th  EU   PVSEC,  Paris,  June  7-­‐11  2004.    

lamp

16  

QE Equipment   Applica0ons   Cells  &   Modules   Cells  

 Light  source

 Wavelength

 Beam

   

 1  kW  Xe    

 280-­‐2000  nm  68  -­‐  10  nm    bandpass  filters  

 cm  to  m  in  diameter  

 150  W  Xe  

 350-­‐2800  nm  3  -­‐  gra*ngs  

 1  by  3  mm  minimum  

17  

NREL  QE  systems  

The  spectral  responsivity  is   measured  with  a  filter  based   system  (280-­‐1800  nm)  or  a   gra*ng  based  system   350-­‐2800  nm  

18  

19  

NREL  Gra0ng  QE  system   Acton  SpectraPro   500i  3  Gra*ng   monochrometer  

150  W   Xe   Arc  lamp  

Spherical  Mirror  

Order   sor*ng   Filter  

Bias  light   Light   Chopper  

PV  Sample  

Computer  

USB  

USB  to     GPIB  

Vacuum  stage  with     thermoelectric  temperature   control  (5-­‐80°C)  

GPIB  

SRS  Model  SR810   Lock-­‐in  Amplifier  

SRS  Model  SR570   Current  Preamplifier  

RS-­‐232  

20  

Module  I-­‐V  Equipment   Test bed

area

min / max V

min / max I



Large Area Continuous Simulator (LACSS)

filtered 25 kW Xe

150 x 120 cm

±0.1 mV

±10 µA



Continuous CLASS AAA



±300 V

±60 A

Spatial nonuniformity dominant error

±3.9% uncertainty in Pmax with 95% confidence limit from formal error analysis

Error in Pmax dominated by error in Isc



Standard Outdoor Measurement System (SOMS)

fixed tilt adjusted monthly,

No constraints

±0.1 mV

±1 µA

Adjustable azimuth & elevation



±300 V

±60 A

lowest error in Isc because zero uniformity error

temperature related errors dominant



Spire model 4600SLP

200 x 137 cm

0.08 mV

0.1 mA

2 Xe flash lamps



150 V

20 A

50 to 80 ms pulse duration

Pulsed CLASS AAA

Spatial nonuniformity dominant is error source. This can be minimized by a reference module of the same size and cell arrangement as what is being tested.

Excellent repeatability (